WorksheetsACR 202 Midterm Exam.
Total questions: 40
Worksheet time: 20mins
Which of the following is not a major component of the Refrigeration cycle?
compressor
condenser
evaporator
suction-line drier
To throttle or regulate the flow of fluid as opposed to just starting or stopping it is called .............
pulsing
modulating
rationing
mixing
The purpose of the crankcase pressure regulating-valve is to
maintain constant pressure in the crankcase.
maintain constant pressure in the evaporator.
prevent a compressor from going into a vacuum.
prevent a compressor overload condition.
The ........... valve can move in very small increments to either open or close the suction line in response to the discharge air temperature of a refrigerated case.
electronic evaporator pressure regulator
thermostatic expansion
electronic expansion
crankcase pressure regulator
An automatic pump down system may be used to
maintain a constant evaporator pressure during low load conditions.
raise the head pressure during low ambient conditions.
prevents surges of liquid refrigerant from entering the compressor during start up.
prevents liquid refrigerant from being trapped in the receiver.
On a one-time or non-short-cycle pump down system
a leaking solenoid valve or discharge valve will cause the system to turn back on.
only the thermostat calling again for cooling will take the system out of pump down.
the refrigerant is stored in the receiver and must be manually released back into the system.
once the system has been pumped down, it will lock out, requiring service.
Two types of relief valves are ...............
check and spring-loaded
manual and ball
spring-loaded and one-time
one-time and multiuse
To prevent the head pressure from dropping to the point where the expansion valve not feed correctly
a pump down system is used.
an evaporator pressure regulator is used.
low ambient controls are used.
a high pressure control is used.
Which of the following is not a method of low ambient control on air-cooled equipment?
Modulating TXV
Fan-cycling controls
Condenser flooding
Fan speed control
Which of the following is used as a protection against low charge or as a temperature control for some refrigeration evaporators?
Oil safety switch
Thermostat
High-pressure switch
Low-pressure switch
Which of the following component is used to protect the compressor and high side components from operating with excessive pressure?
Oil-safety switch
Low-ambient controls
High-pressure switch
Low-pressure switch
Which of the following is a pressure differential control that protects the compressor from inadequate lubrication?
Oil safety switch
compressor thermistor
high-pressure switch
low-pressure switch
A ....................... allows the compressor to cycle on internal overload without affecting the operation of the oil-safety control
oil pressure transducer
current-sensing relay
low-pressure switch
lockout-relay
A type of defrost used by medium-temperature systems that uses the evaporator fans to circulate air over the coil when the compressor is de-energized is called
hot gas defrost
electric heat defrost
readiant defrost
off-cycle defrost
Two methods for accomplishing defrost on low-temperature defrost systems are
radiant and electric defrost
hot-gas and electric defrost
planned and random defrost
hot-gas and off-cycle defrost.
Two types of off-cycle defrost used on medium-temperature systems are
rediant and electric defrost
hot-gas and electric defrost
planned and random defrost
hot-gas and off-cycle defrost
A component used to remove moisture and foreign matter from refrigerant is a(n)
filter drier
receiver
sight-glass
accumulator
The component, located in the suction line, that is used to prevent liquid refrigerant from entering the compressor is called a(n)
filter drier
receiver
refrigerant distributor
accumulator
The component that is used to store liquid refrigerant as it leaves the condenser is called a(n) ............
filter drier
receiver
refrigerant distributor
accumulator
The function of the evaporator pressure regulator is to maintain a
constant evaporator pressure
minimum pressure in the evaporator
constant evaporator temperature
maximum pressure in the evaporator
The component that is used to prevent oil from circulate through the entire system before returning to the compressor crankcase is called a(n)
oil safety control
accumulator
crankcase pressure regulator
oil separator
A(n) ........... is often placed in the suction line leaving the evaporator and improves the evaporator capacity by increasing the liquid subcooling.
heat exchanger
evaporator pressure regulator
refrigerant distributor
oil separator
The component located on the outlet of the liquid receiver that is used to trap the refrigerant in the receiver to perform system service is called a(n)
schrader valve
refrigerant distributor
king valve
electronic evaporator pressure regulator
Condenser flooding maintain head pressure by
filling the receiver with liquid refrigerant, raising the head pressure.
splitting the condenser into 2 equally sized condensers, referred to as summer and summer/winter.
storing refrigerant in the evaporator during the off cycle.
backing up liquid refrigerant in the condenser, acting like an overcharge.
A component that has a magnetic coil, can be normally open or normally closed and is used to control fluid flow is a
solenoid valve.
current sensing relay.
refrigerant check valve.
lockout relay.
................ are snap-acting valves that open and close very fast when the electrical energy is applied to the coil.
Contactors
Condensers
Relays
Solenoid valves
Random defrost is accomplished .................
with a timer
using a high pressure control
using a low pressure control
when the system has enough reserve capacity to cool more than the load requirement
Defrost using internal heat is accomplished using ..............
a sail switch
electric heating elements
hot gas from the compressor
mullion heaters
When a system pumps down, where is the refrigerant stored?
Condenser and receiver.
Evaporator and compressor
Condenser and compressor.
Both a and c.
The normal position for a suction service valve during normal operation is ..........
back-seated
front-seated
mid-seated
Any of the three.
Two-temperature operation of a refrigeration system is necessary when .......
the compressor must be protected from overloading
more than one evaporator is used with a compressor
the coil in the evaporator is excessively long
a multi-circuit distributor is used
Frequently on smaller condensing units, one fan will run continuously and the other fan will be cycled on and off with a(n) .............
ambient temperature controller
ambient pressure valve
thermal expansion valve
thermal control valve
How does the receiver ensure that only 100% liquid refrigerant enters the liquid line?
By means of a dip tube.
It only allows refrigerant to enter the liquid line when it is filled with liquid.
The spring-loaded relief valve opens
None of the above are correct.
Which of the following is another type of low-ambient temperature head pressure control?
Air volume control using shutters and fan cycling.
Programmed defrost timer.
Timer and liquid line solenoid for automatic pump down.
Compressor internal heat.
The refrigeration compressor motor can be operated at about .................. % over its rated capacity without harm during the pulldown.
5
10
15
20
To protect the compressor during periods of hot pull down, a(n) ........ valve is used.
TXV
EPR
CPR
LAC
The EPR valve is installed in the suction line at the evaporator outlet and it ........
modulates the refrigerant vapor to the compressor
prevents the boiling point in the evaporator from dropping below a pre-set point
along with a TXV valve maintains a contant superheat and prevents the pressure from going too low
All of the above.
Which of the following is a type of low-ambient temperature head pressure control?
CPR
EPR
Fan cycling
Off-cycle defrost
EPR valves are also referred to as .......... valves.
DRP
ORC
ORN
ORI
Refrigeration systems are designed to operate year round. For this reason they are equipped with ....................
relief valves
a low-ambient control
oversized evaporator coils
EEPR valves
